A new Approach to Determine the Main Dimensions of Complex Cam Mechanisms

摘要

The synthesis process of cam mechanisms consists of three basic tasks. Besides the definition of the output motion and the calculation of the cam curvature, one of these tasks is the determination of the main dimensions. Among others, the hodograph method is an often-applied method to determine those main dimensions. In special, this method detects the appropriate locations of the cam disk's revolute joint in order to fulfill a predefined minimal transmission angle. For complex cam mechanisms consisting of more than three links, no such method is defined yet. Therefore, this paper describes a new approach for the determination of these main dimensions. This approach is based on the graphical superposition. The relative velocities of the cam follower will be separated into two parts - one part according to the motion of the cam and another part according to the motion of a guidance link. By this superposition, the area of suitable positions of the cam disk's revolute joint can be determined analytically. This determination ensures - like the common hodograph method - that the transmission angle will not fall below a predefined minimal value. After the description of the new approach, it is validated on a complex guidance mechanism with two rotary cam disks.